WordPress plugin that offers "Social networking in a box". BuddyPress is free and open source, and unlike hosted services, BuddyPress allows you to stay in control of your site and create a customized, unique experience.

Live blogging tool with interactive features for real-time audience engagement. Commentary publishes like instant messages, and you can drop in polls, videos, pictures, ads and audio clips. Take comments and questions from readers with control over what gets published.

Croquet is a powerful open source software development environment for the creation and large-scale distributed deployment of multi-user virtual 3D applications and metaverses that are (1) persistent (2) deeply collaborative, (3) interconnected and (4) interoperable. The Croquet architecture supports synchronous communication, collaboration, resource sharing and computation among large numbers of users on multiple platforms and multiple devices.

Hosted collaboration platform. Users can share ideas across their organization, get feedback from people with whom they wouldn't normally interact and form ad hoc groups that cut across organizational boundaries.

DokuWiki is a standards compliant, simple to use Wiki, mainly aimed at creating documentation of any kind. It is targeted at developer teams, workgroups and small companies. It has a simple but powerful syntax which makes sure the datafiles remain readable.

DreamTeam is the leading Project Management application on the AppExchange, and the best solution for Project Management, Collaborative Calendaring, and Document Management in salesforce.com. Supports US and International date standards.

FLOSS Manuals is a wiki-like platform for generating user manuals for free, libre, and open source software (FLOSS). The goal of the project is to make free software more accessible by providing clear documentation that accurately explains their purpose and use. The manuals on FLOSS Manuals are written by a community of people, who do a variety of things to keep the manuals as up to date and accurate as possible. The way in which FLOSS Manuals are written mirrors the way in which FLOSS (Free, libre open source) software itself is written: by a community who contribute to and maintain the content.

Google Wave is an online tool for real-time communication and collaboration. A wave can be both a conversation
and a document where people can discuss and work together using richly formatted text, photos, videos, maps, and more.

GroupServer is an open-source collaboration server, licenced under the GPL. It supports many-to-many, and one-to-many, interaction in groups and communities via email and a Web interface. GroupServer sites are secure, and personalised with member directories, postings by topic, Web Feeds, document sharing, advanced searching, e-mail digests, and Web-based forum management and many other features.

Collaboration platform for groups. Combines the features of discussion forums, email lists, calendars and social networks. Groupsites can be configured to be public, semi-public, or private and secure. Formerly known as CollectiveX.

InstantPresenter offers live video and audio web conferencing and webcasting tools with features such as PowerPoint™ support, live presentation recording and archiving, live polling, screen and desktop sharing, attendance tracking and monitoring.

M2Screen Annotator is a program which will allow you to directly draw on the screen during a presentation or something like that with your Microsoft Tablet PC or Tablet PC SDK enabled system. You can then save the entire screenshot as an image

A web-based collaboration tool geared specifically toward committees and boards, it allows you to easily create and share agendas, minutes and documents as well as schedule meetings and notify members.

Web delivered software service providing email groups for organizations. Email groups have a forum-like web interface with no ads, and can be created on a custom site at a subdomain of onlinegroups.net. Public groups are free. Uses the open source tool GroupServer.

Openfire (formerly Wildfire) is a real time collaboration (RTC) server dual-licensed under the Open Source GPL and commercially. It uses the only widely adopted open protocol for instant messaging, XMPP (also called Jabber).

Professional wiki collaboration software for workgroup collaboration. ProjectForum is a wiki for small-medium teams who need to collaborate. Comes in limited free and licensed options. Also an instruction-oriented version called Course Forum (see the web site).

ProjectPier is a Free, Open-Source, self-hosted PHP application for managing tasks, projects and teams through an intuitive web interface. ProjectPier will help your organization communicate, collaborate and get things done Its function is similar to commercial groupware/project management products, but allows the freedom and scalability of self-hosting. Even better, it will always be free.

Social Actions is an open source database of actions people can take on any issue. The actions in its database are aggregated from across the social web and include everything from volunteer opportunities to micro credit loans.

Social Actions encourages social tech programmers to develop web applications that intelligently distribute the actions in its database across the websites, social networks, and mobile phones that millions of people use every day. The overarching goal of Social Actions' work is to make the web more action-oriented, or in other words, to make it easier for people to find and share opportunities to make a difference.

The Social Source Commons is a “knowledge commons” that provides users with: a directory of software applications; links to relevant documentation, localization tools, services, user reviews; and a place to request tools/features.

The term Social VPN refers to a Virtual Private Network that is created among individual peers, automatically, based on relationships established by them through a social networking service. A SocialVPN aims at providing peer-to-peer network connectivity between an user and his or her friends, in an easy to setup manner that hides from the users the complexity in setting up and maintaining authenticated/encrypted end-to-end VPN tunnels.

StatusNet is the open source microblogging platform that helps you share and connect in real-time within your own domain. With StatusNet you can encourage collaboration, build and engage your community, and be in command of your brand.

StreamLink Software provides nonprofit organizations with web-based management software that increases operational capacity and efficiency. Our philosophy is to maximize the value of every dollar a nonprofit organization has, increasing its ability to accelerate its mission.

With Thumbstacks.com, you can make presentations - like slideshows, or outlines - right in your web browser. When you're done, you can share your presentations with anyone, anywhere, just by sending them a link.

Tiki Wiki CMS Groupware is a full-featured, web-based, multilingual (35+ languages), tightly integrated, all-in-one Wiki+CMS+Groupware, Free Source Software (GNU/LGPL), using PHP, MySQL, Zend Framework, jQuery and Smarty. It is actively developed by a very large international community. Tiki can be used to create all kinds of Web applications, sites, portals, knowledge base, intranets, and extranets.

Tiki offers a very large number of features "out-of-the-box", arguably more than any other Open Source Web Application. Highly configurable and modular, all features are optional and administered via a web-based interface.

TWiki is an enterprise wiki, enterprise collaboration platform and knowledge management system. It is a Structured Wiki, typically used to run a project development space, a document management system, a knowledge base, or any other groupware tool

Based in the eLearning world, Blackboard Collaborate's “vOffice” version—their least expensive—is notably academic-focused. Features include breakout rooms, polls, online content library and much more. vOffice was originally developed by Elluminate inc. and in June 2011 it was acquired by Blackboard Collaborate.

A hosted service to make it easy to work in groups. Have group emails, text messages, folders, calendars, links and meetings. Designed to bring all of group communication pathways into a central, simple place, Wiggio provides a place for social collaboration.

Open source brainstorming and mind mapping software tool developed by XMind Ltd. It helps people to capture ideas, organize to various charts, and share them for collaboration. Supporting mind maps, fishbone diagrams, tree diagrams, org-charts, logic charts, and even spreadsheets.